The periodic fuel combustion processes within an internal combustion engine and the generally nonlinear engine geometry result in torque disturbances and crankshaft speed oscillations. These crankshaft speed oscillations adversely effect the smoothness and quality of the vehicle's ride, cause increased noise, vibration and harshness ("NVH"), and undesirably reduce fuel economy. Typically, a conventional "passive" flywheel is coupled to the end of the crankshaft to reduce the pulsation of the crankshaft speed.
Conventional flywheels are relatively massive and undesirably increase the overall weight and packing space of the vehicle's engine, and undesirably reduce fuel economy. Additionally, the effectiveness of flywheels in damping crankshaft speed oscillations is severely limited since conventional flywheels are "passive", devices and are incapable of adjusting to changing operating conditions and circumstances.
There is therefore a need for a system for damping crankshaft speed oscillations which overcomes the drawbacks of prior systems and methods and which utilizes an active supplemental torque source such as a starter-alternator to attenuate crankshaft speed oscillations.